It's difficult on what to tell you.. you say you want to breed "king" bettas, you also got a pair of deltas.. so we can't say to get one thing if you are going to breed __, because if you do breed kings then we will recommend _x_ size.

For your "king bettas" you are going to want more than a gallon for each fish. For your average betta you will want minimal of 32oz, but upwards of .66 - .75 gallons to give them the proper room to grow enough to sell/ship.

You also plan to have 20-30 breeding pairs that you will need to house individually and keep them heated.. so those will need a different size to house.

It costs hundreds to set up a proper breeding set up, for 1-2 spawns.. I spent well over a thousand for a 2 spawn set up personally (there are cheaper ways, but money not an issue so got actual tanks, etc). Have to do it properly to be successful and worth the money and hours spent on a breeding program. If you lack space, now may not be a time to do it.. or may have to breed on a small scale, that way you can have a bit larger containers to properly grow the juveniles in. For your white deltas you have, 32oz would be the smallest, but after a bit would move them into double that size as to not stunt them any.

I live close enough to one of their warehouses that I did not have to pay shipping when I picked up my cases. They even loaded the jars into my car for me. Generally speaking wholesale prices are better than retail.

I used to work at acm. It's a store that's only located on the east coat. They do sell 16 and 32oz mason jars for around $1 and change. There's always coupons so you could easily get them for $.50 each if you purchased them one at a time, or if you bought in bulk they often have 20-25% off sales so you could also get them for pretty cheap that way. They generally aren't in high demand (at least at the store I worked at) so they great thing about that meant they were always in stock even during sales.